CN102506896A - Device and method for testing back scattering noise in resonator optical gyro (ROG) by resonant cavity technology - Google Patents

Abstract

The invention discloses a device and a method for testing back scattering noise in a resonator optical gyro (ROG) by resonant cavity technology. On the basis of the ROG system structure, a resonance curve is measured, and asymmetry of the resonant curve before and after back scattering noise suppression is calibrated and compared to obtain the influence of the back scattering noise on the gyro system. The device for testing back scattering noise in a ROG comprises a scan signal generator, a laser, a first coupler, a first phase modulator, a second phase modulator, a first circulator, a second circulator, a second coupler, an annular resonant cavity, a first photodetector, a second photodetector, a first modulation signal generator, and a second modulation signal generator. The invention provides a novel method for testing back scattering noise in a ROG, can directly carry out testing in a ROG system, and has an important scientific significance and application values.

Description

Backward scattering noise device and method in the resonator cavity technical testing resonance type optical gyroscope

Technical field

The present invention relates to backward scattering noise device and method in a kind of resonator cavity technical testing resonance type optical gyroscope.

Background technology

Resonance type optical gyroscope (Resonator Optic Gyro; ROG) be a kind of high precision inertial sensor based on Sagnac effect realization angular velocity detection, it is through detecting the angular velocity of rotation that obtains object in the resonator cavity clockwise with the resonance frequency difference of counterclockwise propagating light beam.Than the interfere type optical gyroscope, resonance type optical gyroscope miniaturization and integrated on have greater advantage.

In the ring resonator of resonance type optical gyroscope; Need to introduce simultaneously (Clockwise clockwise; CW) and counterclockwise (Counterclockwise; CCW) two-beam of direction, the back-scattering light that produces when CW direction light beam transmits in resonator cavity is a kind of interference to the CCW light beam, vice versa.Because resonance type optical gyroscope requires light source to have high coherence, the backscattering noise has become one of main optical noise that influences the Gyro Precision raising.To the backward scattering Research on Noise, usually, need the size of each point backscattering coefficient in the logical test resonator cavity, find the solution through the mode of distribution integration and obtain backward scattering noise effect size.

Existing backward scattering noise testing method is to produce sawtooth wave through signal generator (Signal Generator) laser instrument output light frequency is scanned, after laser instrument output light gets into resonator cavity; Through resonator cavity, (Photodetector PD) detects it part light to utilize photodetector along the CW direction; Can obtain the resonance curve of output, another part light returns along the CCW direction, forms back-scattering light; Utilize photodetector that it is detected, can obtain the backward scattering curve of output, the maximum backward scattering peak resonant degree of depth is compared; Just can access backscattering coefficient; To there be the resonator cavity of corresponding backward scattering characteristic to be applied to the resonance type optical gyroscope system,, calculate backward scattering noise effect size through theoretical derivation.

Summary of the invention

The objective of the invention is to overcome the deficiency of prior art, backward scattering noise device and method in the resonator cavity technical testing resonance type optical gyroscope is provided.

Backward scattering noise device comprises sweep generator, laser instrument, first coupling mechanism, first phase-modulator, second phase-modulator, first circulator, second circulator, second coupling mechanism, ring resonator, first photodetector, second photodetector, first modulation signal generator and second modulation signal generator in the resonator cavity technical testing resonance type optical gyroscope; Sweep generator, laser instrument, first coupling mechanism, one end connect in order; The first coupling mechanism other end is divided into counterclockwise and clockwise two-way: counterclockwise one tunnel first phase-modulator, first circulator, second coupling mechanism, ring resonator are connected in order; Clockwise one tunnel second phase-modulator, second circulator, second coupling mechanism, ring resonator connect in order; First modulation signal generator is connected with first phase-modulator; First circulator is connected with second photodetector, and second modulation signal generator is connected with second phase-modulator, and second circulator is connected with first photodetector.

The method of backward scattering noise is in the resonator cavity technical testing resonance type optical gyroscope: in the gyrosystem; Sweep generator scans laser instrument; Laser instrument output light is divided into counterclockwise and clockwise two-way after through first coupling mechanism; Lead up to first phase-modulator, first circulator by first modulation signal generator modulation counterclockwise, get into ring resonator behind second coupling mechanism, lead up to second phase-modulator, second circulator by the modulation of second modulation signal generator clockwise; Get into ring resonator behind second coupling mechanism; Behind ring resonator, through first photodetector counterclockwise one road signal is carried out demodulation output, through second photodetector clockwise one road signal is carried out demodulation output; With clockwise one road light is example, and when not having the backward scattering noise, the detected light intensity signal of second photodetector has only the light intensity of clockwise one road light; When having the backward scattering noise; The detected light intensity of second photodetector is except that clockwise one road signal light intensity; Also comprise counterclockwise one tunnel backward scattering light intensity; And the relevant light intensity between clockwise one road light and counterclockwise one road back-scattering light, there is degree of asymmetry η 1 in tuning curve, output accuracy is produced the influence of Δ Ω 1; After the method that adopts different modulating frequency and carrier suppressed; The backward scattering noise is inhibited; Make the relevant light intensity between counterclockwise one tunnel backward scattering light intensity and clockwise one road light and counterclockwise one road back-scattering light all be suppressed, the detected light intensity of second photodetector has only signal light intensity, and there is degree of asymmetry η 2 in tuning curve; Output accuracy is produced the influence of Δ Ω 2; Relatively tuning curve degree of asymmetry η 1 and η 2 before and after the backward scattering squelch, and Δ Ω 1 and Δ Ω 2 can access the influence of backward scattering noise to gyro output; The method is applicable to the fiber annular resonant cavity to be the resonance type optical fiber gyro of core sensitive element and to be the resonance type integrated optical gyroscope of sensitive element with the optical waveguide resonator cavity.

The invention provides the method for backward scattering noise in a kind of novel test resonance type optical gyroscope; Tuning curve through the test resonator cavity; Tuning curve degree of asymmetry before and after the contrast carrier suppressed; Directly obtain backward scattering noise effect size in the resonance type optical gyroscope, have important scientific meaning and using value.

Description of drawings

Fig. 1 is a backward scattering noise-measuring system structural representation provided by the invention;

Fig. 2 (a) is that carrier wave is 40MHz, and index of modulation M is 1 o'clock, the frequency spectrum after phase modulation (PM);

Fig. 2 (b) is that carrier wave is 40MHz, and index of modulation M is 2.405 o'clock, the frequency spectrum after phase modulation (PM);

Fig. 3 is before and after the backward scattering squelch, and the tuning curve degree of asymmetry is synoptic diagram relatively;

Among the figure: sweep generator 1, laser instrument 2, first coupling mechanism 3, first phase-modulator 4, second phase-modulator 5, first circulator 6, second circulator 7, second coupling mechanism 8, ring resonator 9, first photodetector 10, second photodetector 11, first modulation signal generator 12, second modulation signal generator 13.

Embodiment

As shown in Figure 1, backward scattering noise device comprises sweep generator 1, laser instrument 2, first coupling mechanism 3, first phase-modulator 4, second phase-modulator 5, first circulator 6, second circulator 7, second coupling mechanism 8, ring resonator 9, first photodetector 10, second photodetector 11, first modulation signal generator 12 and second modulation signal generator 13 in the resonator cavity technical testing resonance type optical gyroscope; Sweep generator 1, laser instrument 2, first coupling mechanism, 3 one ends connect in order; First coupling mechanism, 3 other ends are divided into counterclockwise and clockwise two-way: counterclockwise one tunnel first phase-modulator 4, first circulator 6, second coupling mechanism 8, ring resonator 9 are connected in order; Clockwise one tunnel second phase-modulator 5, second circulator 7, second coupling mechanism 8, ring resonator 9 connect in order; First modulation signal generator 13 is connected with first phase-modulator 4; First circulator 6 is connected with second photodetector 11, and second modulation signal generator 12 is connected with second phase-modulator 5, and second circulator 7 is connected with first photodetector 10.

The method of backward scattering noise is in the resonator cavity technical testing resonance type optical gyroscope: in the gyrosystem; 1 pair of laser instrument 2 of sweep generator scans; Laser instrument 2 output light are divided into counterclockwise and clockwise two-way after through first coupling mechanism 3; First phase-modulator 4, first circulator, 6, the second coupling mechanisms, 8 backs of leading up to counterclockwise by the modulation of first modulation signal generator 13 get into ring resonators 9, lead up to second phase-modulator 5, second circulator 7 by 12 modulation of second modulation signal generator clockwise; Second coupling mechanism, 8 backs get into ring resonator 9; Behind ring resonator 9, carry out demodulation output through 10 pairs of counterclockwise one road signals of first photodetector, carry out demodulation output through 11 pairs of clockwise one road signals of second photodetector; With clockwise one road light is example, and when not having the backward scattering noise, second photodetector, 11 detected light intensity signals have only the light intensity of clockwise one road light; When having the backward scattering noise; Second photodetector, 11 detected light intensity are except that clockwise one road signal light intensity; Also comprise counterclockwise one tunnel backward scattering light intensity; And the relevant light intensity between clockwise one road light and counterclockwise one road back-scattering light, there is degree of asymmetry η 1 in tuning curve, output accuracy is produced the influence of Δ Ω 1; After the method that adopts different modulating frequency and carrier suppressed; The backward scattering noise is inhibited; Make the relevant light intensity between counterclockwise one tunnel backward scattering light intensity and clockwise one road light and counterclockwise one road back-scattering light all be suppressed, second photodetector, 11 detected light intensity have only signal light intensity, and there is degree of asymmetry η 2 in tuning curve; Output accuracy is produced the influence of Δ Ω 2; Relatively tuning curve degree of asymmetry η 1 and η 2 before and after the backward scattering squelch, and Δ Ω 1 and Δ Ω 2 can access the influence of backward scattering noise to gyro output; The method is applicable to the fiber annular resonant cavity to be the resonance type optical fiber gyro of core sensitive element and to be the resonance type integrated optical gyroscope of sensitive element with the optical waveguide resonator cavity.

In the method based on backward scattering noise in the resonator cavity technical testing resonance type optical gyroscope:

Laser instrument output light E _FL-out(t)=E ₀Exp (j ω t) behind first coupling mechanism 3, is divided into (CW) and (CCW) two-way clockwise counterclockwise; With CW road light is example, gets into ring resonators 9 via second phase-modulator 5, second circulator 7, second coupling mechanism, 8 backs, again via first circulator 6; Carry out demodulation output through 11 pairs of signals of second photodetector; When not having the backward scattering noise, second photodetector, 11 detected light have only the flashlight on CW road, can be expressed as

$E_{\mathrm{PD}2}\left(t\right)=E_0{e}^{\mathrm{j\&omega;t}}{u}_{\mathrm{<figure-callout\; id="1"\; label="CW"\; filenames="111019161248.png,111019161251.png"\; state="\{\{state\}\}">CW</figure-callout>}}^{1/2}(T-R\frac{e^{-\mathrm{j\&omega;\&tau;}}}{1-Q{e}^{-\mathrm{j\&omega;\&tau;}}})---\left(1\right)$

u _CW＝k _C1(1-α _C1)(1-α _PM2)(1-α _CL2)(2)

Wherein, k _C1, α _C1Be respectively the coupling coefficient and insertion loss, α of first coupling mechanism 3 _PM2Be the insertion loss of second phase-modulator 5, α _CL2It is the loss of second circulator 7; τ=Ln ₀/ c, for light in ring cavity 9, transmit one the week transit time, n ₀Be refractive index, c is the light velocity in the vacuum.

$T=\sqrt{(1-k_{C2})(1-{\mathrm{\&alpha;}}_{C2})}---\left(3\right)$

$R=t_f{k}_{C2}(1-{\mathrm{\&alpha;}}_{C2})\sqrt{1-{\mathrm{\&alpha;}}_R}---\left(4\right)$

$Q=t_f\sqrt{(1-k_{C2})(1-{\mathrm{\&alpha;}}_{C2})(1-{\mathrm{\&alpha;}}_R)}---\left(5\right)$

$t_f=\sqrt{1-{\mathrm{\&alpha;}}_L\&CenterDot;L}---\left(6\right)$

Wherein, k _C2, α _C2Be respectively the coupling coefficient and insertion loss of second coupling mechanism 8, L is that ring resonator 9 chambeies are long, α _LBe the unit length waveguide loss; α _RBe luminous power backscattering rate.

According to formula I=c ε E ², can light intensity be expressed as

${\mathrm{<figure-callout\; id="2"\; label="I\; PD"\; filenames="111019161248.png"\; state="\{\{state\}\}">I</figure-callout>}}_{\mathrm{PD}}=c{\mathrm{\&epsiv;}}_0<{\left|{\mathrm{<figure-callout\; id="2"\; label="E\; PD"\; filenames="111019161248.png"\; state="\{\{state\}\}">E</figure-callout>}}_{\mathrm{PD}}\right|}^2>=[T^2-\frac{2\mathrm{TR}{(\cos \mathrm{\&omega;\&tau;}-Q)-\left(R\right)}^2}{1+{\left(Q\right)}^2-2Q\cos \mathrm{\&omega;\&tau;}}]u_{\mathrm{CW}}{I}_0---\left(7\right)$

Wherein, I ₀=c ε ₀E ₀ ², represent initial light intensity, order

$\mathrm{\&rho;}=1-\frac{T^2{(1-Q)}^2-2\mathrm{TR}(1-Q)+{\left(R\right)}^2}{{(1-Q)}^2(1-{\mathrm{\&alpha;}}_c)}---\left(8\right)$

$L\left(\mathrm{\&delta;}\right)=\frac{{(1-Q)}^2}{{(1-Q)}^2+4Q{\sin }^2(\mathrm{\&delta;}/2)}---\left(9\right)$

I then _PD2Can be expressed as

I _PD2＝u _CW(1-α _C)I ₀[1-ρL(δ)] (10)

Wherein, δ=ω τ, expression light is around the ring resonator phase delay in 9 one weeks.

Consider the influence of the backscattered light on CCW road to the CW road, definition CCW direction is the z direction, and ring resonator 9 incidence points are the point of z=0, write out from the light beam of CCW direction input ring resonator 9, and the electric field of arbitrfary point can be expressed as in loop

$E_i(z,t)=\sqrt{k_C(1-{\mathrm{\&alpha;}}_C)(1-{\mathrm{\&alpha;}}_{l}z)}{u}_{\mathrm{<figure-callout\; id="1"\; label="CCW"\; filenames="111019161248.png,111019161251.png"\; state="\{\{state\}\}">CCW</figure-callout>}}^{1/2}{\mathrm{<figure-callout\; id="0"\; label="E"\; filenames="111019161253.png"\; state="\{\{state\}\}">E</figure-callout>}}_0\underset{m=0}{\overset{\&infin;}{\mathrm{\&Sigma;}}}{\left(Q\right)}^m{e}^{-\mathrm{jm\&omega;\&tau;}}{e}^{j(\mathrm{\&omega;t}-\mathrm{\&beta;z}+\mathrm{\&Delta;\&theta;})}---\left(11\right)$

u _CCW＝(1-k _C1)(1-α _C1)(1-α _PM1)(1-α _CL1)(12)

Wherein, Δ θ representes the phase differential into CCW before the ring and CW direction light field, α _PM1Be the insertion loss of first phase-modulator 4, α _CL1It is the loss of first circulator 6.CCW gets into light beam z=z in ring of ring resonator 9 _sBe scattered, scattered light is propagated along the CW direction, order

This moment without the light wave of electric field stack at z=0 point backscattering electric field E _sCan be expressed as

$E_s(z_s,t)=\frac{\sqrt{{\mathrm{\&alpha;}}_R}(1-{\mathrm{\&alpha;}}_l{z}_s)t_a{u}_{\mathrm{<figure-callout\; id="1"\; label="CCW"\; filenames="111019161248.png,111019161251.png"\; state="\{\{state\}\}">CCW</figure-callout>}}^{1/2}{E}_0{e}^{-\mathrm{j\&eta;}}\exp \left[j(\mathrm{\&omega;t}+\mathrm{\&Delta;\&theta;}-2\mathrm{\&beta;}{z}_s)\right]}{1-{\mathrm{Qe}}^{-\mathrm{j\&omega;\&tau;}}}---\left(13\right)$

Wherein, η representes the phase relation between incident electric field and the scattered field.The light wave of process electric field stack is at z=0 point backscattering electric field dE _PD2-sCan be expressed as

${\mathrm{dE}}_{\mathrm{PD}2-s}(z_s,t)=t_a\underset{n=0}{\overset{\&infin;}{\mathrm{\&Sigma;}}}{Q}^n{E}_s(z_s,t-\mathrm{n\&tau;})---\left(14\right)$

The method of employing loop integral is calculated, and can obtain at the backward scattering electric field that second photodetector 11 records doing

$E_{\mathrm{PD}2-s}={\&Integral;}_{z_s=0}^{z_s=L}{\mathrm{dE}}_{\mathrm{PD}2-s}(z_s,t)---\left(15\right)$

The backward scattering light intensity, for

$I_{\mathrm{PD}2-s}=c{\mathrm{\&epsiv;}}_0{E}_{\mathrm{PD}2-s}(z_s,t)\&CenterDot;E_{\mathrm{PD}2-s}*(z_s,t)={\mathrm{\&alpha;}}_{R}L\{{[\frac{\mathrm{\&rho;}}{1-{\mathrm{<figure-callout\; id="2"\; label="t\; f"\; filenames="111019161248.png"\; state="\{\{state\}\}">t</figure-callout>}}_f^{}}\&CenterDot;L\left(\mathrm{\&delta;}\right)]}^2+$

$\frac{2T[{(T\&CenterDot;t_f)}^2-Q^2]}{{[1-{(T\&CenterDot;t_f)}^2]}^2(1-Q^2)}\&CenterDot;\frac{\mathrm{\&rho;}}{1-{\mathrm{<figure-callout\; id="2"\; label="t\; f"\; filenames="111019161248.png"\; state="\{\{state\}\}">t</figure-callout>}}_f^{}}\&CenterDot;L\left(\mathrm{\&delta;}\right)\}{I}_0---\left(16\right)$

By above-mentioned analysis, can obtain the total light intensity I that records at second photodetector 11 ₂Can be expressed as

$I_2(z,t)=c{\mathrm{\&epsiv;}}_0<{|{\mathrm{<figure-callout\; id="2"\; label="E\; PD"\; filenames="111019161248.png"\; state="\{\{state\}\}">E</figure-callout>}}_{\mathrm{PD}}+E_{\mathrm{PD}2-s}|}^2>$

$=c{\mathrm{\&epsiv;}}_0<{\mathrm{<figure-callout\; id="2"\; label="E\; PD"\; filenames="111019161248.png"\; state="\{\{state\}\}">E</figure-callout>}}_{\mathrm{PD}}\&CenterDot;E_{\mathrm{<figure-callout\; id="2"\; label="PD"\; filenames="111019161248.png"\; state="\{\{state\}\}">PD</figure-callout>}2}^{*}>+c{\mathrm{\&epsiv;}}_0<E_{\mathrm{PD}2}\&CenterDot;E_{\mathrm{PD}2-s}^{*}+E_{\mathrm{PD}2-s}\&CenterDot;E_{\mathrm{PD}2}^{*}>$

$+c{\mathrm{\&epsiv;}}_0<E_{\mathrm{PD}2-s}\&CenterDot;E_{\mathrm{PD}2-s}^{*}>---\left(17\right)$

First expression CW direction signal light light intensity is suc as formula (10); The 3rd expression backscattering light intensity is suc as formula (16); Relevant light intensity between the back-scattering light of second expression CW direction light and CCW direction.

For the light intensity of backscattered light itself, the method that can take CW road and CCW road to be applied the different frequency modulation signal overcomes; For the relevant light intensity between backscattered light and the flashlight, can it be suppressed through the method for carrier suppressed.

The carrier suppressed technology is meant in the resonance type optical gyroscope that adopts sine wave modulation, through changing the index of modulation of modulation signal, a kind of method that the carrier wave item in the signal is inhibited.With CW road signal is example, and second modulation signal generator, 13 generation amplitudes are V ₁, angular frequency is ω ₁Sine wave when second phase-modulator 4 is modulated, the signal after the modulation is:

$E_{\mathrm{CW}-\mathrm{in}}\left(t\right)=E_0{u}_{\mathrm{<figure-callout\; id="1"\; label="CW"\; filenames="111019161248.png,111019161251.png"\; state="\{\{state\}\}">CW</figure-callout>}}^{1/2}\exp (\mathrm{j\&omega;t}+M\sin {\mathrm{\&omega;}}_{1}t)---\left(18\right)$

Wherein, M=V ₁(π/V _π), be the index of modulation, V _πHalf-wave voltage for phase-modulator.Can expand into n rank Bessel's function:

$E_{\mathrm{CW}-\mathrm{in}}\left(t\right)=E_0{u}_{\mathrm{<figure-callout\; id="1"\; label="CW"\; filenames="111019161248.png,111019161251.png"\; state="\{\{state\}\}">CW</figure-callout>}}^{1/2}\underset{n=-\&infin;}{\overset{\&infin;}{\mathrm{\&Sigma;}}}{J}_n\left(M\right)\mathrm{expj}(\mathrm{\&omega;}+n{\mathrm{\&omega;}}_1)t---\left(19\right)$

One of n=0 is carrier wave.Adjustment through to the modulation signal amplitude can change the size of index of modulation M, thereby the carrier wave item is played inhibiting effect in various degree.Fig. 2 (a) is that index of modulation M is 1 o'clock frequency spectrum after phase modulation (PM); Fig. 2 (b) is that index of modulation M is 2.405 o'clock frequency spectrums after phase modulation (PM); ω=40MHz wherein, ω ₁=9MHz.Fig. 2 explains under the different indexes of modulation can obtain different carrier signals.When M=2.405, J ₀(M)=0, carrier wave can be suppressed fully.After carrier wave is suppressed fully, just can eliminate the influence of the coherent light between backscattered light and the flashlight.

When backward scattering light intensity and relevant light intensity not being suppressed, three part light intensity signals all can be detected output by photodetector, and there is certain degree of asymmetry in tuning curve; After the method that adopts different modulating frequency and carrier suppressed; The backward scattering noise is inhibited, and makes backward scattering light intensity and relevant light intensity all be suppressed, and the detected light intensity of photodetector has only signal light intensity; But because the existence of other noises; Still there is certain degree of asymmetry in tuning curve, but before being suppressed than the backward scattering noise, degree of asymmetry can change.Through demarcating and compare the degree of asymmetry of backward scattering squelch front and back tuning curve, just can access of the influence of backward scattering noise to gyro output.

Fig. 3 is suppressed the tuning curve of front and back for the backward scattering noise; The longitudinal axis is normalization light intensity I/I0, and transverse axis is normalized frequency f/FSR, and FSR is free line width (the Free Spectral Range of ring resonator; FSR), be meant the spacing of adjacent two resonance frequencies: FSR=c/n ₀L.Among the figure, dotted line is the tuning curve before the backward scattering squelch, and solid line is the tuning curve after the backward scattering squelch, respectively the tuning curve degree of asymmetry before and after the backward scattering squelch is demarcated:

Before the backward scattering noise was suppressed, degree of asymmetry η 1 can be expressed as

$\mathrm{\&eta;}1=\frac{|\mathrm{Wa}1-\mathrm{<figure-callout\; id="1"\; label="Wb"\; filenames="111019161248.png,111019161251.png"\; state="\{\{state\}\}">Wb</figure-callout>}1|}{|\mathrm{<figure-callout\; id="1"\; label="Wa"\; filenames="111019161248.png,111019161251.png"\; state="\{\{state\}\}">Wa</figure-callout>}1+\mathrm{<figure-callout\; id="1"\; label="Wb"\; filenames="111019161248.png,111019161251.png"\; state="\{\{state\}\}">Wb</figure-callout>}1|}---\left(20\right)$

Converting frequency variation into does

$\mathrm{\&Delta;<figure-callout\; id="1"\; label="f"\; filenames="111019161248.png,111019161251.png"\; state="\{\{state\}\}">f</figure-callout>}1=\frac{\mathrm{\&Gamma;}1\&CenterDot;\mathrm{\&eta;}1}{2}---\left(21\right)$

Wherein, Γ 1 is a full width at half maximum, Γ 1=|Wa1+Wb1|.

Again according to formula:

$\mathrm{\&Delta;f}=\frac{D}{\mathrm{n\&lambda;}}\mathrm{\&Delta;\&Omega;}---\left(22\right)$

Wherein, n is a refractive index, and λ is a signal light wavelength, and D is the diameter of ring, and Δ Ω is the rotational angular velocity variable quantity.Can obtain the rotation error amount that the backward scattering noise exists before being suppressed does

$\mathrm{\&Delta;\&Omega;}1=\frac{\mathrm{n\&lambda;}}{D}\mathrm{\&Delta;f}1---\left(23\right)$

After the backward scattering noise was suppressed, degree of asymmetry η 2 can be expressed as:

$\mathrm{\&eta;}2=\frac{|\mathrm{Wa}2-\mathrm{<figure-callout\; id="2"\; label="Wb"\; filenames="111019161248.png"\; state="\{\{state\}\}">Wb</figure-callout>}2|}{|\mathrm{<figure-callout\; id="2"\; label="Wa"\; filenames="111019161248.png"\; state="\{\{state\}\}">Wa</figure-callout>}2+\mathrm{<figure-callout\; id="2"\; label="Wb"\; filenames="111019161248.png"\; state="\{\{state\}\}">Wb</figure-callout>}2|}---\left(24\right)$

Converting frequency variation into does

$\mathrm{\&Delta;<figure-callout\; id="2"\; label="f"\; filenames="111019161248.png"\; state="\{\{state\}\}">f</figure-callout>}2=\frac{\mathrm{\&Gamma;}2\&CenterDot;\mathrm{\&eta;}2}{2}---\left(25\right)$

Wherein, Γ 2 is a full width at half maximum, Γ 2=|Wa2+Wb2|.

The rotation error amount that exists after the backward scattering noise is suppressed does

$\mathrm{\&Delta;\&Omega;}2=\frac{\mathrm{n\&lambda;}}{D}\mathrm{\&Delta;f}2---\left(26\right)$

Relatively tuning curve degree of asymmetry η 1 and η 2 before and after the backward scattering squelch, and Δ Ω 1 and Δ Ω 2 just can access the influence of backward scattering noise to gyro output.

Claims (2)

1. backward scattering noise device in the resonator cavity technical testing resonance type optical gyroscope is characterized in that comprising sweep generator (1), laser instrument (2), first coupling mechanism (3), first phase-modulator (4), second phase-modulator (5), first circulator (6), second circulator (7), second coupling mechanism (8), ring resonator (9), first photodetector (10), second photodetector (11), first modulation signal generator (12) and second modulation signal generator (13); Sweep generator (1), laser instrument (2), first coupling mechanism (3) one ends connect in order; First coupling mechanism (3) other end is divided into counterclockwise and clockwise two-way: counterclockwise one tunnel first phase-modulator (4), first circulator (6), second coupling mechanism (8), ring resonator (9) are connected in order; Clockwise one tunnel second phase-modulator (5), second circulator (7), second coupling mechanism (8), ring resonator (9) connect in order; First modulation signal generator (13) is connected with first phase-modulator (4); First circulator (6) is connected with second photodetector (11); Second modulation signal generator (12) is connected with second phase-modulator (5), and second circulator (7) is connected with first photodetector (10).

2. the method for backward scattering noise in the resonator cavity technical testing resonance type optical gyroscope that installs according to claim 1 of a use; It is characterized in that: in the gyrosystem; Sweep generator (1) scans laser instrument (2); Laser instrument (2) output light is divided into counterclockwise and clockwise two-way after through first coupling mechanism (3); Lead up to first phase-modulator (4), first circulator (6) by first modulation signal generator (13) modulation counterclockwise, second coupling mechanism (8) back gets into ring resonator (9), leads up to second phase-modulator (5), second circulator (7) by second modulation signal generator (12) modulation clockwise; Second coupling mechanism (8) back gets into ring resonator (9); Behind ring resonator (9), through first photodetector (10) counterclockwise one road signal is carried out demodulation output, through second photodetector (11) clockwise one road signal is carried out demodulation output; With clockwise one road light is example, and when not having the backward scattering noise, the detected light intensity signal of second photodetector (11) has only clockwise one road signal light intensity; When having the backward scattering noise; The detected light intensity of second photodetector (11) is except that clockwise one road signal light intensity; Also comprise counterclockwise one tunnel backward scattering light intensity, and the relevant light intensity between clockwise one road light and counterclockwise one road back-scattering light, there is degree of asymmetry in tuning curve η1, the influence that output accuracy is produced Δ Ω 1; After the method that adopts different modulating frequency and carrier suppressed; The backward scattering noise is inhibited; Make the relevant light intensity between counterclockwise one tunnel backward scattering light intensity and clockwise one road light and counterclockwise one road back-scattering light all be suppressed; The detected light intensity of second photodetector (11) has only signal light intensity, and there is degree of asymmetry in tuning curve η2, to the influence that output accuracy produces Δ Ω 2, compare backward scattering squelch front and back tuning curve degree of asymmetry η1 draw η2, and Δ Ω 1 and Δ Ω 2, can access of the influence of backward scattering noise to gyro output; The method is applicable to the fiber annular resonant cavity to be the resonance type optical fiber gyro of core sensitive element and to be the resonance type integrated optical gyroscope of sensitive element with the optical waveguide resonator cavity.

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